The present invention relates to telescopic aluminum step ladders, and more particularly relates to a side rails fastening mechanism for securing the side rails of a telescopic aluminum step ladders into shape when it is in use, or into collapsed condition to minimize space occupation when it is not in use.
Regular aluminum step ladders are generally of fixed type, the front and rear pair of side rails of which may be closed up together but can not be respectively collapsed in vertical direction to greatly reduce space occupation when not in use. There is a kind of folding aluminum step ladders which can be folded up to reduce space occupation when not in use. Still there is provided a kind of telescopic aluminum step ladders the side rails of which are each comprised of a plurality frame fractions that slide one inside another. However, regular folding or telescopic aluminum step ladders are not very satisfactory in use. They may be complicated in structure and difficult to set up and collapse or not very stable for supporting heavy load. The present invention has been accomplished to eliminate the aforesaid disadvantages of the conventional aluminum step ladders.